Soil fertility and productivity of rice (Oryza sativa)-wheat (Triticum aestivum) cropping system in an Inceptisol as influenced by integrated nutrient management

A long term (I985-97) field experiment was carried out on Inceptisol with rice (Oryza sativa L.)-wheat (Triticum aestivum L. emend Fiori and Paol.) sequence to study the effect of integrated nutrient management on grain yield, straw yield, nutrient uptake and availability of nutrients in the soil. The results revealed that an 25% substitution of chemical fertilizer N through organics, viz famyard manure and green manuring of dhaincha (Sesbania acaleata L.) resulted significantly higher yield of rice up to 1993 than 50% NPK through organics while yield values were at par during last three years of cropping (1994-96). Among the different organic sources of N, farmyard manure and green manuring of dhaincha proved better than crop residues in increasing grain and straw yield and nutrient uptake by rice. Addition of farmyard manure and green manuring of dhaincha registered their residual effect on the succeeding wheat crop by producing higher uptake of nutrient and grain and straw yield of wheat. lntegrated use of inorganic and organics through farmyard manure, crop residues of wheat and green manuring of dhaincha improved the organic carbon, cation ex-change capacity and water·holding capacity significantly with remarkable decrease in bulk density. Available nitrogen, phosphorus, potassium and sulphur increased significantly with organic sources of nutrient over their initial status of soil. Micronutrient cations were decreased in purely inorganic treated plots over control while remarkable build up in these cations was noted in organic treated plots.